Cereus Food Poisoning Research Articles

ＬＣ‐ＭＳを用いたセレウス菌嘔吐毒産生試験に関する検討

Two types of food poisoning from Bacillus cereus, the emetic type caused by emetic toxins and the diarrhea type caused by enterotoxins, have been reported . Most cases in Japan are the emetic type, therefore, the cereulide needs to be proven when B. cereusfood poisoning is suggested. The original detection method for cereulide is performed by microscopic assessment of vacuole formation in HEp-2 cells, but it involves some judgement problems that require adept skills as well as reproducibility of the result. Furthermore, it also requires considerable labor to obtain and maintain the cells. Recently, an analysis method using liquid chromatography-mass spectrometry (LC-MS), which shows excellent accuracy, quantification, specificity and reproducibility is often used to detect cereulide. In this paper, we compared Nutrient broth containing manganese and glucose (NB+Mn) medium as previously recommended and 10% skim milk medium for the production of cereulide, and further investingated the influence of heat-treatment process of culture fluid on the recovery of cereulide measured by LC-MS.

Epidemiological typing of Bacillus cereus by amplified fragment length polymorphism.

A simple amplified fragment length polymorphism method was developed for the epidemiological typing of Bacillus cereus. The method was applied to 21 cultures from seven food poisoning and eight non-food poisoning incidents. Results were compared with those obtained by conventional serotyping using flagellar antigens and assessed in relation to epidemiological data. Amplified fragment length polymorphism was found to be highly reproducible and 16 different profiles (each unique to the 15 incidents) were recognized. The method was also able to discriminate three subtypes within serotype H1, which is responsible for the majority of the emetic type of B. cereus food poisoning in England and Wales.

The adhesion of Bacillus cereus spores to epithelial cells might be an additional virulence mechanism

Four out of ten Bacillus cereus strains produced spores able to adhere to monolayers of Caco-2 cells (human epithelial cells). One of these strains has been involved in an outbreak of food poisoning where the symptoms were more severe and persisted for longer than a normal B. cereus food poisoning. The hydrophobicity of the spores is a contributing factor for the adhesion to occur. The spores are able to germinate in an environment similar to that of the small intestine and then the vegetative cells can produce the enterotoxin directly at the target place. A concentrated and active form of the enterotoxin will be taken up by the epithelial cells in the small intestine. Spore adhesion could be an important virulence factor for some B. cereus strains.

What problems does the food industry have with the spore-forming pathogens Bacillus cereus and Clostridium perfringens?

Spore-forming bacteria are special problems for the food industry. It is not always possible to apply enough heat during food processing to kill spores, thus we have to take advantage of knowledge of the spore-formers to control them. For the meat industry Clostridium perfringens might become a special problem, although this bacterium mainly causes food poisoning through food served in restaurants, hospitals or homes for elderly people (Cliver, 1987; Reynolds, 1987; Gondrosen et al., 1990). The reason for the food poisoning is always the same: meat-containing dishes stored after cooking with insufficient cooling and reheating (Granum, 1990). Even though it should be relatively easy to control this kind of food poisoning, C. perfringens is still one of the most common sources of foodborne diseases. Proper disinfection is necessary to control this type of food poisoning, as it is now clear that only kitchen strains of C. perfringens are able to produce the large amounts of enterotoxin necessary to cause food poisoning (Granum, 1990; Cornillot et al., 1995). Bacillus cereus is more difficult to control, specifically in the dairy industry, where it is now causing the main problems. Insufficient heating of rice-containing dishes has been known to cause B. cereus food poisoning of the emetic kind for a long time (Kramer and Gilbert, 1989), but will not be dealt with in this paper. There are several reasons for the problems in the dairy industry. First of all it seems to be impossible to completely avoid the presence of B. cereus in all milk samples. Secondly the spores are very hydrophobic (Husmark, 1993), and will attach to the surfaces of the pipelines of the dairy industry, where they might multiply and resporulate. A third problem is that pasteurisation heating is insufficient to kill the spores, while competition from other vegetative bacteria is eliminated. It seems that several B. cereus strains have become psychrotrophic over the years, making possible growth at temperatures as low as 4-6 degrees C (Granum et al., 1993a). None of the methods used to control hygiene in the dairy industry so far are able to control B. cereus. This is a continuously increasing problem for the industry but, with emerging knowledge, we should be able to control it. In this paper we will discuss the problems the food industry is facing with C. perfringens and B. cereus, and how these problems might be solved. We will also give our view on how research might ease these problems in the future.

Distribution of toxigenic Bacillus cereus in rice samples marketed in Hong Kong

Eleven of 16 samples of rice on sale in rice shops and supermarkets in Hong Kong contained Bacillus cereus. Although B. cereus counts did not exceed 100 bacteria/g in most of the positive samples, a sample of Thai red rice and a poor quality rice originating from China contained between 300 to 1000 cells/g and 10(4) to 2×10(5) cells/g, respectively. Nine strains produced an enterotoxin responsible for the diarrhoeal-type B. cereus food poisoning and seven of these strains also produced a haemolysin (haemolysin BL), a dermonecrotic vascular permeability factor which may be a virulence determinant in diarrhoeal illness caused by this bacterium.

From the Centers for Disease Control and Prevention. Bacillus cereus food poisoning associated with fried rice at two child day care centers--Virginia, 1993

From the Centers for Disease Control and Prevention. Bacillus cereus food poisoning associated with fried rice at two child day care centers--Virginia, 1993

Plasmid, serotypic, and enterotoxin analysis of Bacillus cereus in an outbreak setting.

Bacillus cereus is a recognized agent of food-borne disease. In this report we describe an outbreak of B. cereus gastroenteritis associated with consumption of beef stew among patients and staff at a Rhode Island nursing home. The beef had been improperly stored after preparation. The predominant symptoms of the illness were cramps and diarrhea; it lasted an average of 16 h. No deaths occurred. The organism was recovered from 10 of 23 stools collected from ill patients and 1 of 21 stools collected from controls (P = 0.0044, Fisher's two-tailed exact test). All isolates had the same biotype and serotype, newly designated H.26; all elaborated the diarrheal B. cereus enterotoxin when tested in rabbits by the vascular permeability reaction; and all had identical plasmid profiles, which differed from those of B. cereus strains selected randomly from other outbreaks. Plasmid analysis may prove to be a useful new tool in investigating outbreaks of B. cereus food poisoning.

Properties and production characteristics of vomiting, diarrheal, and necrotizing toxins of Bacillus cereus

Evidence is provided that the enterotoxin of Bacillus cereus variously described in the literature as diarrheagenic toxin, diarrheal agent, fluid accumulation factor, vascular permeability factor, dermonecrotic toxin, and intestinonecrotic toxin is a single relatively unstable protein of molecular weight approximately 50,000 and isoelectric point of the order of 4.9. It is presumed to be the enterotoxin responsible for the diarrheal-type B. cereus food poisoning syndrome and it may also be the pyogenic and pyrogenic factor in nongastrointestinal B. cereus infections of man and animals. The enterotoxin is a vegetative growth metabolite produced to one degree or another by almost all B. cereus strains and is readily separated from phospholipase and heat-labile cereolysin but less readily differentiated from a heat-stable hemolysin. It is lethal to mice but may also be separable from another mouse lethal factor by electrofocusing. The emetic toxin responsible for the vomiting-type B. cereus food poisoning syndrome is clearly distinguishable from the diarrheal and other toxic factors and appears to be a highly stable compound of molecular size <5000.

Extracellular factor synthesized by Bacillus cereus which evokes a dermal reaction in guinea pigs.

A guinea pig skin assay was developed as a measure of ileal loop fluid-inducing factor in the rabbit and possibly of the causative principle of Bacillus cereus food poisoning. A green or bloody necrotic reaction was produced in the guinea pig skin by injection of culture filtrates from 21 of 24 B. cereus strains tested, and by no other Bacillus species tested except for the closely related B. thuringiensis. The skin factor was synthesized and excreted by logarithmically growing cells, inactivated by heating at 56 C for 5 min, precipitable by ammonium sulfate, and was nondialyzable. The skin activity was not related to the lecithinolytic or hemolytic activities of B. cereus. Production of the skin factor depended on the medium in which the culture was growing. The factor was an antigenically active substance. There are indications that at least two antigenically distinct species of skin factors exist.